Carburetor



Feb. 20, 1934. c. c. SANDS CARBURETOR Filed Aug. 25, 1951 I WM/Zt/ENTO f Patented Feb. 20, 1934 CARBURETOR Charles C. Sands, Cleveland, Ohio, assignor'to Zenith-Detroit Corporation, Detroit, Mich., a corporation-of Michigan 2 Application August 25, 1931. Serial No. 559,222

art of carburetion, and more particularly to improved means for supplying combustible mixtures to internal combustion engines under such con- 5 trolled conditions that objectionable gassing is prevented.

In the art to which the present invention relates, it is customary to provide a carburetor for supplying the necessary combustible charge to the engine. Such carburetors are responsive, generally, to suction conditions, in such manner that as the manifold depression increases, greater and greater quantities of fuel are delivered to the engine for a given position of the throttle. In the operation more especially of busses and trucks, it has been found that there is an objectionable gassing condition each time the vehicle, after having attained appreciable speed, is decelerated. To effect deceleration, the driver closes the throttle, but the carcontinues running on its momentum, thus turning over the motor at a speed which is greater than that which the motor would assume for the position to which the throttle has been moved. There is thus produced a depres-, sion in the manifold which is higher than that at normal idling speed, thus causing an increase in fuel delivery at a time when fuel is not needed. It is this increase in fuel which causes gassing. This gassing condition increases as the speed change increases, or in other words, becomes more and more objectionable the greater the rapidity of deceleration.

In accordance with the present invention, there ,is provided a charge forming device responsive to manifold conditions in such manner as to subject the float chamber to a sub-normal pressure condition upon deceleration of the engine, thus cutting down the free tendency of the fuelto enter the mixing chamber of the carburetor and thereby obviating the tendency toward gassing.

In the accompanying figure of the drawing, which is largely diagrammatic, there is shown for purposes of illustration olly, one form of the pres ent invention.

through a suitable nozzle structure, not shown.

Any usual form of air inlet 4 may be provided.

Extending upwardly from the mixing chamher is a manifold 5, by means of which the com- Referring more particularly to the-drawing,-

10 Claims. H (01. 261-72) bustible mixture is delivered to the engine in known manner. Within the mixing chamber there is provided the usual form of throttle shaft 6 carrying a suitable throttle valve for controlling the passage of the combustible mixture-to the manifold.

Extending upwardly from the cover 7, of the float chamber, is a connection 8 communicating at one end with the interior of the float chamber above the fuel level therein, and at its opposite end with the interior of'a valve casing 9. Within the valve casing, there is provided a valve 10, of the plunger or sliding type, normally held in the position illustrated by means of a spring 11. For varying the seating pressure exerted by the 7 spring, there may be provided suitable adjusting means 12.

Also communicating with the interior of the valve casing 9, is a pair of pressure connections 14 and 15, respectively, herein illustrated as con- 7 nected to the manifold 5 above the throttle valve, through the medium of suitable tubes or conduits 16.

With the construction shown and described, it will be apparent that under normal operating conditions the vacuum in the manifold will not be sufficient to overcome the adjusted pressure of the spring 11 and thus move the valve 10. Should the operator of the vehicle, however, accelerate the same to a fairly high speed, such as normally represented by a substantially wide open throttle position, and then suddenly close the throttle and decelerate, the manifold vacuum will quickly build up to a point where the pres- I sure of the spring will be'overcome, and the valve 10 moved to the left as viewed in the drawing.

It will be apparent that this movement is obtained by reason of the fact that the left hand end of the valve will be subjected to a sub-normal pressure condition through the connection 15. while the right hand end of the valve will be subjected to normal atmospheric pressure through the port 17. Upon a predetermined movement of the valve 10, an annular groove 18 in the valve will establish communication between the connections 8 and 14, thus subjecting the fuel in the float'chamber to the sub-normal pressure condition' obtaining in the manifold. This depression on the float chamber may amount to approximately four to six inches of water, and is sufiicient to entirely stop the fuel flow-from the jet or nozzle structure. As soon, however, as the manifold vacuum comes back to normal, i. e., when the vehicle reaches an idling or substantially an idling speed, the valve will resume its 9 bit normal position as illustrated in the drawings, thus establishing normal pressure conditions in the float chamber and permitting a normal fuel flow through the jet or nozzle structure into the mixing chamber.

By cutting 01f the flow of fuel from the carburetor substantially concomitantly with the deceleration of the vehicle, the continuing supply of fuel under such conditions that it is not consumed by the engine, is prevented, and the objectionable gassing condition incident to deceleration is en-,- tirely obviated.

I have found that not only does a slide valve of the general construction herein illustrated,

. having a second pressure connection to a source possess decided advantages over poppet valves and ball valves, but that the two connections 14 'and 15, one for operating the valve and one for establishing the desired sub-normal pressure in the float chamber, are highly desirable. With a single connection, or with valves of the poppet or ball type, I have found that considerable difliculty is experienced in attempting to overcome an objectionable vibrating condition. While such structures are within the scope ofmy invention, it is to be understood that I prefer to employ a sliding valve for the reasons stated, and further prefer to employ two separate connections having the functions ascribed thereto.

By reference to the drawing, it will be noted that the float chamber is provided with the usual vent, so.indicated, and that the connection 8 is provided at a suitable point intermediate the ends thereof with an appreciable restriction. Inasmuch as it is not necessary to produce in the float chamber a depression equal to the manifold depression, but only a sufiicient depression to hold back the flow of gasoline to the jet structure, the ratio between the vent in the float chamber and the restriction in the connection 8 is such that the desired fraction of the suction obtaining in the manifold will be impressed on the air within the float chamber above the fuel. In, this manner sucking of the fuel from the float chamber through the connection 8 is completely obviated.

The advantages of the present invention arise from the provision of an improved carburetor structure by means of which the fuel flow under predetermined conditions of operation 'may be automatically checked, and thereby obviate objectionable gassing incident to vehicle deceleration.

While I have herein illustrated and described a preferred embodiment of my invention, it will be understood that changes in the construction and operation of the parts may be made without departing either from the spirit of the present invention or the scope of my broader claims.

I claim:

1. In, a carburetor including a float chamber vented to the atmosphere, a slide valve having a transverse opening for controlling the pressure condition within the float chamber, and a sepa rate pressure responsive connection for sliding said valve.

2. The combination with a carburetor including a float chamber and throttle, of a mani fold, a valve having separate, connections to said manifold above the curburetor throttle, one of said connections being effective for operating said valve and the other connection being adapted to communicate with the float chamber upon movement of said valve.

3. The combination with a carburetor including a float chamber and a throttle, of a manifold connected to the carburetor above said throttle, a valve having a connection with said manifold for operating the valve and a second connection with said manifold effective upon movement of said valve for subjecting the float cham her to sub-normal pressure.

4. A de-gassing device for carburetors, comprising a float chamber having a pressure connection communicating therewith, a valve casing communicating with said pressure connection and of sub-normal pressure, a valve in said casing for normally cutting oif communication between said pressure connections, and a third connection to said source for operating said valve.

5. A de-gassing device for carburetors, comprising a float chamber having a pressure connection communicating therewith, a valve casing communicating with said pressure connection and having a second pressure connection to a source of subnormal pressure, a valve in said casing for normally cutting oif communication between said pressure connections, and a third connection to said source for operating said valve, said valve being normally yieldingly urged in one direction against said operating pressure.

6. The combination witha carburetor having a constant level chamber and a manifold, of means including a slide valve responsive to pressure conditions in said manifold and eifective when said slide valve is moved to one position for subjecting the constant level chamber of the carburetor to a sub-normal pressure.

'7. The combination with a carburetor having a constant level chamber and a manifold, of means including a valve responsive to pressure conditions in said manifold and effective for subjecting the constant level chamber of the carburetor to a sub-normal pressure, said valve being of the slide type yieldingly urged in one direction.

8. The combination with a carburetor including a float chamber, of a manifold, a valve casing having three pressure connections thereto,

tion passage communicating with said valve for effecting operation thereof.

10. In a carburetor .including a float chamber having a suction passage leading thereto, a valve intersecting said passage and normally cutting off the float chamber from the suction source, and

a separate suction passage communicating with said valvefor effecting operation thereof, said valve being of the slide type normally subjected to atmospheric pressure at one portion thereof.

CHARLES C. SANDS. 

